Purification method and system for lithium-extraction dissolving-solution of aluminum electrolysis waste

Abstract

A purification method and system for a lithium-extraction dissolving-solution of an aluminum electrolysis waste, the method includes: adding an alkaline mixture to the lithium-extraction dissolving-solution until a pH of the lithium-extraction dissolving-solution reaches a first target pH, and filtering the lithium-extraction dissolving-solution to obtain a first filtrate after performing a first reaction in the lithium-extraction dissolving-solution; the first target pH is 11.5˜12; and adding a decalcification agent and a catalyst to the first filtrate until a pH of the first filtrate reaches a second target pH, and filtering the first filtrate to obtain a purified dissolving-solution after performing a second reaction in the first filtrate, the second target pH being 11.5˜12.

1 . A purification method for a lithium-extraction dissolving-solution of an aluminum electrolysis waste, comprising:
 adding an alkaline mixture into the lithium-extraction dissolving-solution until a pH of the lithium-extraction dissolving-solution reaches a first target pH and performing a first reaction in the lithium-extraction dissolving-solution, and then filtering the lithium-extraction dissolving-solution to obtain a first filtrate, wherein the alkaline mixture comprises a regulator and a stabilizer; the regulator is added into the lithium-extraction dissolving-solution after the stabilizer is added into the lithium-extraction dissolving-solution; the stabilizer comprises a calcium sulfate; the regulator comprises a calcium oxide and/or a calcium hydroxide; and the first target pH is 11˜11.5; and   adding a decalcification agent and a catalyst to the first filtrate until a pH of the first filtrate reaches a second target pH and performing a second reaction in the first filtrate, and then filtering the first filtrate to obtain a purified dissolving-solution, the second target pH being 11.5˜12.   
     
     
         2 . The purification method according to  claim 1 , wherein an addition amount of the stabilizer makes a mass volume ratio of the stabilizer to the lithium-extraction dissolving-solution to be 6 kg/m 3  to 10 kg/m 3 ; and/or
 an addition amount of the regulator is an amount that makes the pH of the lithium-extraction dissolving-solution reach the first target pH.   
     
     
         3 . The purification method according to  claim 1 , wherein, the decalcification agent comprises a sodium carbonate; an actual addition amount of the sodium carbonate is 1.5 to 3.0 times a theoretical addition amount of the sodium carbonate; the theoretical addition amount of the sodium carbonate is determined by a concentration of calcium ions in the first filtrate; and/or
 the catalyst comprises a sodium hydroxide, an addition amount of the sodium hydroxide makes a mass volume ratio of the sodium hydroxide to the first filtrate to be 0.2 kg/m 3  to 0.5 kg/m 3 .   
     
     
         4 . The purification method according to  claim 1 , wherein, a time of the first reaction is 30 to 60 minutes after the pH of the lithium-extraction dissolving-solution reaches the first target pH; and/or
 the second reaction comprises a decalcification reaction and a catalytic reaction, the decalcification reaction being performed for 20 to 30 minutes, and then the catalytic reaction being performed for 20 to 30 minutes.   
     
     
         5 . The purification method according to  claim 1 , further comprising:
 adding a sodium carbonate to purify the purified dissolving-solution for a second time if a concentration of calcium ions in the purified dissolving-solution is greater than 50 mg/L; and   purifying the purified dissolving-solution for the second time using a resin if the concentration of the calcium ions in the purified dissolving-solution is 10 mg/L to 50 mg/L.   
     
     
         6 . A purification method for a lithium-extraction dissolving-solution of an aluminum electrolysis waste, comprising:
 adding an alkaline mixture into the lithium-extraction dissolving-solution until a pH of the lithium-extraction dissolving-solution reaches a first target pH and performing a first reaction in the lithium-extraction dissolving-solution, and then filtering the lithium-extraction dissolving-solution to obtain a first filtrate and a first filter residue, respectively, wherein the alkaline mixture comprises a regulator and a stabilizer, and the regulator is added into the lithium-extraction dissolving-solution after the stabilizer is added into the lithium-extraction dissolving-solution; the stabilizer comprises a calcium sulfate, and the regulator comprises a calcium oxide and/or a calcium hydroxide; and the first target pH is 11˜11.5; and   adding a decalcification agent and a catalyst into the first filtrate until a pH of the first filtrate reaches a second target pH and performing a second reaction in the first filtrate, and then filtering the first filtrate to obtain a purified dissolving-solution and a second filter residue, respectively; and   washing the first filter residue and the second filter residue by adding a washing liquid into the first filter residue and the second filter residue to form a washing slurry, and then filtering the washing slurry to obtain a washing filtrate, and returning the washing filtrate into the lithium-extraction dissolving-solution for a treatment.   
     
     
         7 . The purification method according to  claim 6 , wherein an addition amount of the stabilizer makes a mass volume ratio of the stabilizer to the lithium-extraction dissolving-solution to be 6 kg/m 3  to 10 kg/m 3 ; and/or
 an addition amount of the regulator is an amount that makes the pH of the lithium-extraction dissolving-solution reach the first target pH.   
     
     
         8 . The purification method according to  claim 6 , wherein, the decalcification agent comprises a sodium carbonate; an actual addition amount of the sodium carbonate is 1.5 to 3.0 times a theoretical addition amount of the sodium carbonate; the theoretical addition amount of the sodium carbonate is determined by a concentration of calcium ions in the first filtrate; and/or
 the catalyst comprises a sodium hydroxide, an addition amount of the sodium hydroxide makes a mass volume ratio of the sodium hydroxide to the first filtrate to be 0.2 kg/m 3  to 0.5 kg/m 3 .   
     
     
         9 . The purification method according to  claim 6 , wherein, a time of the first reaction is 30 to 60 minutes after the pH of the lithium-extraction dissolving-solution reaches the first target pH; and/or
 the second reaction comprises a decalcification reaction and a catalytic reaction, the decalcification reaction being performed for 20 to 30 minutes, and then the catalytic reaction being performed for 20 to 30 minutes.   
     
     
         10 . The purification method according to  claim 6 , further comprising:
 adding a sodium carbonate to purify the purified dissolving-solution for a second time if a concentration of calcium ions in the purified dissolving-solution is greater than 50 mg/L; and   purifying the purified dissolving-solution for the second time using a resin if the concentration of the calcium ions in the purified dissolving-solution is 10 mg/L to 50 mg/L.   
     
     
         11 . The purification method for the lithium-extraction dissolving-solution of the aluminum electrolysis waste according to  claim 6 , wherein a liquid-solid ratio of the washing liquid to the first filter residue and/or the second filter residue during the washing is 3:1 to 4:1; and/or
 the number of times for the washing is 1 time˜2 times.   
     
     
         12 . A purification system for a lithium-extraction dissolving-solution of an aluminum electrolysis waste, the system being used in the method according to  claim 1 , the system comprising at least two purification devices, the purification devices comprising:
 a filter unit ( 1 ), comprising a liquid-reception tray ( 11 ), a stir motor ( 12 ), a scraper ( 13 ) and a filter screen ( 14 ), wherein the filter screen ( 14 ) is disposed at a bottom surface of the liquid-reception tray ( 11 ); an output end of the stir motor ( 12 ) is connected to the scraper ( 13 ); and the scraper ( 13 ) is disposed above the filter screen ( 14 ); and   a liquid-reception unit ( 2 ), comprising a liquid-reception tank ( 21 ), a vacuum interface ( 22 ), a feed port ( 23 ), a discharge port ( 24 ) and a stir paddle ( 25 ), wherein the liquid-reception tank ( 21 ) is disposed directly below the filter screen ( 14 ); the feed port ( 23 ) and the discharge port ( 24 ) are respectively distributed on two sides of the liquid-reception tank ( 21 ), and the vacuum interface ( 22 ) and the discharge port ( 24 ) are disposed on a same side of the liquid-reception tank ( 21 ); the stir paddle ( 25 ) is disposed in the liquid-reception tank ( 21 ), and the stir paddle ( 25 ) is fixedly connected to an extended end of the stir motor ( 12 ).   
     
     
         13 . The purification system according to  claim 12 , further comprising: a residue discharge unit ( 3 ), comprising a shovel truck ( 31 ), a shovel-truck lane ( 32 ), and a filter residue groove ( 33 ),
 wherein the shovel-truck lane ( 32 ) is disposed on an upper portion of the liquid-reception tank ( 21 ), is located below the filter screen ( 14 ), and is disposed around an open end of the liquid-reception tank ( 21 ); the shovel truck ( 31 ) slides in the shovel-truck lane ( 32 ) to remove filter residues filtered by the filter screen ( 14 ); and the filter residue groove ( 33 ) is disposed on a side of the liquid-reception tank ( 21 ).   
     
     
         14 . The purification system according to  claim 13 , further comprising a shovel-truck baffle ( 34 ), which is disposed on the shovel truck ( 31 ) and is located at a position opposite to a direction of rotation movement of the shovel truck ( 31 ). 
     
     
         15 . The purification method for the lithium-extraction dissolving-solution of the aluminum electrolysis waste according to  claim 7 , wherein a liquid-solid ratio of the washing liquid to the first filter residue and/or the second filter residue during the washing is 3:1 to 4:1; and/or
 the number of times for the washing is 1 time˜2 times.   
     
     
         16 . The purification method for the lithium-extraction dissolving-solution of the aluminum electrolysis waste according to  claim 8 , wherein a liquid-solid ratio of the washing liquid to the first filter residue and/or the second filter residue during the washing is 3:1 to 4:1; and/or
 the number of times for the washing is 1 time˜2 times.   
     
     
         17 . The purification method for the lithium-extraction dissolving-solution of the aluminum electrolysis waste according to  claim 9 , wherein a liquid-solid ratio of the washing liquid to the first filter residue and/or the second filter residue during the washing is 3:1 to 4:1; and/or
 the number of times for the washing is 1 time˜2 times.   
     
     
         18 . The purification method for the lithium-extraction dissolving-solution of the aluminum electrolysis waste according to  claim 10 , wherein a liquid-solid ratio of the washing liquid to the first filter residue and/or the second filter residue during the washing is 3:1 to 4:1; and/or
 the number of times for the washing is 1 time˜2 times.